Embodiments of the present specification relate generally to physiological monitoring, and more particularly to systems and methods for enhanced estimation of physiological parameters using an array of magnetic sensors.
Continual monitoring of a patient's physiological parameters such as vital signs and/or blood flow characteristics allows for early detection of physiological anomalies, thus providing timely alerts for life saving interventions. Particularly, routine use of multi-parameter monitors in trauma, surgery, and intensive-care unit settings has greatly improved medical outcomes in recent times. By way of example, pulse oximeters, ultrasonic flow meters, and pressure cuff sensors are routinely used for monitoring oxygen saturation (SpO2), cardiac output, and/or blood pressure to aid in detection of life-threatening medical conditions such as arterial hypoxemia, hypovolemia, and/or internal bleeding. However, such conventional physiological monitoring devices are often too large and/or are prohibitively expensive for routine use outside hospitals.
Accordingly, certain portable electrical, mechanical, and optical monitoring devices have been developed to allow for non-invasive monitoring of physiological parameters of patients. Some of these devices, for example, may be implemented in chest stripes, socks attachments, wristwatches, or finger attachments that may be operatively coupled to a patient. However, use of these portable devices entails direct skin contact, complicated processing, insufficient monitoring capabilities, considerable power consumption, and/or need for a trained operator. Furthermore, measurements made using the conventional devices are highly susceptible to motion artifacts caused by patient motion and/or ambient vibrations.
Certain other conventional monitoring methods propose use of miniature and low-powered magnetic sensors to detect a modulated magnetic signature of blood (MMSB) for use in heart rate, blood flow, and pressure monitoring. In these conventional methods, a magnetic sensor is positioned proximal a target region such as a patient's forefinger to continually measure a uniform magnetic field generated by a permanent magnet placed in the vicinity. The magnetic field measurements, in turn, may be used to determine certain physiological parameters such as flow velocity and arterial distention corresponding to the patient based on an empirical model.
Although such empirical models attempt to correlate the magnetic field measurements to certain physiological parameters, the empirical models do not account for certain magnetic properties such as magnetization relaxation of the blood. Furthermore, the empirical models fail to provide an accurate representation of the blood flow, geometry, and magnetic interaction between the blood and the generated magnetic field. Since these conventional models disregard effects of certain magnetic properties of blood on the magnetic field measurements, values of the physiological parameters determined using such conventional monitoring methods may be inaccurate, and thus, unsuitable for clinical use.